物理学报Issue(1)：85-92,8.DOI:10.7498/aps.65.014202
部分相干刃型位错光束的谱Stokes奇点∗
Sp ectral Stokes singularities of partially coherent edge dislo cation b eams
摘要
Abstract
The polarization singularities in vector wavefields have been extensively studied analytically and experimentally. The polarization singularities can be analyzed by using electromagnetic theory or Stokes parameters, or be described in terms of complex Stokes scalar fields. In some practical applications, partially coherent beams have more advantages than fully coherent beams. Recently, the concept of the polarization singularities has been extended from fully coherent beams to partially coherent beams. In this paper, using the representation of cross-spectral density matrix propagation, the explicit propagation expressions for the partially coherent edge dislocation beams are derived in free space, and based on the spectral Stokes parameters the spectral singularities are studied in detail. It is shown that there exist spectral s12, s23 and s31 singularities of partially coherent edge dislocation beams in free-space propagation. s12 singularities correspond to circular polarization (C-points) of the partially coherent edge dislocation beams, and s3>0 (s3<0) means right-(left-) handedness, where the orientations of the major and minor axes of the polarization ellipse become undefined. s23 and s31 singularities must be located on L-lines, where the handedness of the polarization ellipse is undetermined (linear polarization). The motion, creation and annihilation of spectral Stokes singularities may appear in the variation of a controlling parameter, such as off-axis distance, slope of edge dislocation, spatial correlation length, or in the variation of the propagation distance. By suitably varying the spatial correlation length or propagation distance the V-point, the handedness reversal of C-point, creation and annihilation for a pair of oppositely charged spectral singularities take place. The creation and annihilation occur for a pair of s12 singularities with opposite topological charge but same handedness. The critical points of the controlling parameters and propagation distance, at which pairs of different spectral singularities annihilate, are not the same. The collision of the C-point and L-line results in a V-point (vector singularity), which is unstable. A small perturbation leads to the handedness reversal. At such a point the state of polarization is undetermined and the degree of polarization P =0. The results obtained in this paper would be useful for a deep understanding of polarization singularities of stochastic electromagnetic beams.关键词
部分相干光束/刃型位错/谱Stokes奇点Key words
partially coherent beam/edge dislocation/spectral Stokes singularity引用本文复制引用
郑尚彬,唐碧华,姜云海,罗亚梅,高曾辉..部分相干刃型位错光束的谱Stokes奇点∗[J].物理学报,2016,(1):85-92,8.基金项目
国家自然科学基金(批准号:61275203)和四川省教育厅自然科学基金(批准号:15CZ0017)资助的课题.* Project supported by the National Natural Science Foundation of China (Grant No.61275203) and the Natural Science Foundation of the Education Department of Sichuan Province, China (Grant No.15CZ0017) （批准号:61275203）
